The present invention relates to flotation devices and particularly to improvements for devices of this kind.
The limitations of common techniques for providing flotation can be summarized as:
1. Fixed flotation such as foam takes up too much space and is not practical except in the lightest of vessels. PA1 2. Air and watertight compartments are expensive and practical only in the largest of ships, and even then a major flooding of compartments will sink the vessel unless there is another means of internal flotation to resist flooding. PA1 3. Pumps normally do not have the capacity to stay ahead of a flooding condition. PA1 4. Life rafts and personal flotation devices save lives. However, more than personal flotation is needed for any length of time and for survival in heavy weather. In addition, life rafts and personal flotation present a much smaller target for a rescue team than the original vessel, and the original vessel also contains drinking water, a food supply, navigational devices and communications equipment which are not ordinarily transferable to a life raft. PA1 5. Many existing flotation devices require deployment on the outside of a vessel, or van or snowmobile travelling over a frozen lake or stream, subjecting the device to damage or otherwise diminishing its practical use for flotation. PA1 6. Devices fabricated of rubber or rubberized fabric are too heavy and often take up too much space for convenient use for flotation or as spill containment devices.
U.S. Pat. No. 4,887,541 discloses onboard deployable flotation devices placed in strategic positions throughout a vessel to provide positive buoyancy so as to prevent sinking of the vessel. The devices comprise multiple ply construction including inner bag with outer protective cover fitted into portable carryalls or secured in deflated condition to the hull of a vessel. The flotation devices may be located at a point separate from their means of inflation and several flotation devices can be inflated by a common inflation system. Flotation devices of this kind are particularly suited for fishing boats, motorboats and sailboats.
The present invention provides improvements in the field of deployable flotation devices for marine vessels, lift bags for marine salvage, for vehicles operating on the surface of frozen water, and also for spill containment of environmental hazards.